Composite flange from braided preform

ABSTRACT

A preform sheet for a composite component comprises a body section and a flange section. The preform body section includes a plurality of axial tows braided with at least a plurality of first bias tows and a plurality of second bias tows. The preform flange section includes a first braided flange layer and a second braided flange layer. The first braided flange layer is defined by the first and second braided bias tows of the preform body section extending into the flange section. Neither the first nor second braided flange layers have axial tows.

BACKGROUND

Flanges on cylindrical composite parts present certain design andmanufacturing challenges, particularly when the part is made from atriaxial braid. The axial tows of the braid, when oriented in the hoopdirection of the cylinder, preclude the formation of an up-turned flangesince the continuous fibers in the axial tows cannot deform or stretchto conform to the larger diameter of the flange.

SUMMARY

A preform sheet for a composite component comprises a body section and aflange section. The preform body section includes a plurality of axialtows braided with at least a plurality of first bias tows and aplurality of second bias tows. The preform flange section includes afirst braided flange layer and a second braided flange layer. The firstbraided flange layer is defined by the first and second braided biastows of the preform body section extending into the flange section.Neither the first nor second braided flange layers have axial tows.

A gas turbine engine component comprises a tubular body section and aflange section. The tubular body section includes a plurality of fiberwraps encompassed within a matrix composition. The plurality of bodysection fiber wraps each include a plurality of axial tows braided withat least a plurality of first bias tows and a plurality of second biastows. The plurality of axial tows are generally aligned along acomponent circumferential direction. The flange section includes aplurality of fiber wraps encompassed within the matrix composition. Theplurality of flange section fiber wraps each include a first braidedflange layer and a second braided flange layer. The first braided flangelayer is defined by at least the first and second braided bias towsextending into the body section. Neither the first nor second braidedflange layers have axial tows.

A method for making a fabric preform for a composite component compriseslaying out a first article of fabric having a plurality of axial towsbraided with at least a plurality of first bias tows and a plurality ofsecond bias tows. The axial tows are removed from a first portion of thefirst article of fabric, leaving the first fabric portion braided absentan axial tow, and a second fabric portion braided with axial tows. Asecond article of fabric absent an axial tow is disposed along the firstfabric portion to form a reinforced first fabric portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an example gas turbine engine.

FIG. 2A depicts an example flanged composite component for a gas turbineengine.

FIG. 2B shows a cross-section of the example flanged compositecomponent.

FIG. 3A is an example of a braided fabric preform for use in making aflanged composite component.

FIG. 3B illustrates the braided fabric preform with the flanged portionupturned.

FIG. 4A is a schematic depiction of triaxially braided fabric.

FIG. 4B shows one type of biaxially braided fabric.

FIG. 4C shows another type of biaxially braided fabric.

FIG. 5A shows a first triaxially braided sheet of fabric which can beused to make a braided fabric preform for use in making a flangedcomposite component.

FIG. 5B depicts the first sheet of fabric with some axial tows removedto form a first biaxially braided portion and a second triaxiallybraided portion of the sheet.

FIG. 5C shows a second sheet of biaxially braided fabric.

FIG. 5D illustrates the first sheet of fabric having a first portionreinforced by the second fabric sheet.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an example gas turbine engine 20 thatincludes fan section 22, compressor section 24, combustor section 26 andturbine section 28. Alternative engines might include an augmentersection (not shown) among other systems or features. Fan section 22drives air along bypass flow path B while compressor section 24 drawsair in along core flow path C where air is compressed and communicatedto combustor section 26. In combustor section 26, air is mixed with fueland ignited to generate a high pressure exhaust gas stream that expandsthrough turbine section 28 where energy is extracted and utilized todrive fan section 22 and compressor section 24.

Although the disclosed non-limiting embodiment depicts a turbofan gasturbine engine, it should be understood that the concepts describedherein are not limited to use with turbofans as the teachings may beapplied to other types of turbine engines; for example a turbine engineincluding a three-spool architecture in which three spoolsconcentrically rotate about a common axis and where a low spool enablesa low pressure turbine to drive a fan directly, or via a gearbox, anintermediate spool that enables an intermediate pressure turbine todrive an intermediate compressor of the compressor section, and a highspool that enables a high pressure turbine to drive a high pressurecompressor of the compressor section.

The example engine 20 generally includes low speed spool 30 and highspeed spool 32 mounted for rotation about an engine central longitudinalaxis A relative to an engine static structure 36 via several bearingsystems 38. It should be understood that various bearing systems 38 atvarious locations may alternatively or additionally be provided.

Low speed spool 30 generally includes inner shaft 40 that connects fan42 and low pressure (or first) compressor section 44 to low pressure (orfirst) turbine section 46. Inner shaft 40 drives fan 42 directly, orthrough a speed change device, such as geared architecture 48, to drivefan 42 at a lower speed than low speed spool 30. High-speed spool 32includes outer shaft 50 that interconnects high pressure (or second)compressor section 52 and high pressure (or second) turbine section 54.Inner shaft 40 and outer shaft 50 are concentric and rotate via bearingsystems 38 about engine central longitudinal axis A.

Combustor 56 is arranged between high pressure compressor 52 and highpressure turbine 54. In one example, high pressure turbine 54 includesat least two stages to provide a double stage high pressure turbine 54.In another example, high pressure turbine 54 includes only a singlestage. As used herein, a “high pressure” compressor or turbineexperiences a higher pressure than a corresponding “low pressure”compressor or turbine.

The example low pressure turbine 46 has a pressure ratio that is greaterthan about 5. The pressure ratio of the example low pressure turbine 46is measured prior to an inlet of low pressure turbine 46 as related tothe pressure measured at the outlet of low pressure turbine 46 prior toan exhaust nozzle.

Mid-turbine frame 58 of engine static structure 36 is arranged generallybetween high pressure turbine 54 and low pressure turbine 46.Mid-turbine frame 58 further supports bearing systems 38 in turbinesection 28 as well as setting airflow entering low pressure turbine 46.

The core airflow C is compressed by low pressure compressor 44 then byhigh pressure compressor 52 mixed with fuel and ignited in combustor 56to produce high speed exhaust gases that are then expanded through highpressure turbine 54 and low pressure turbine 46. Mid-turbine frame 58includes vanes 60, which are in the core airflow path and function as aninlet guide vane for low pressure turbine 46. Utilizing vane 60 ofmid-turbine frame 58 as the inlet guide vane for low pressure turbine 46decreases the length of low pressure turbine 46 without increasing theaxial length of mid-turbine frame 58. Reducing or eliminating the numberof vanes in low pressure turbine 46 shortens the axial length of turbinesection 28. Thus, the compactness of gas turbine engine 20 is increasedand a higher power density may be achieved.

The disclosed gas turbine engine 20 in one example is a high-bypassgeared aircraft engine. In a further example, gas turbine engine 20includes a bypass ratio greater than about six (6), with an exampleembodiment being greater than about ten (10). The example gearedarchitecture 48 is an epicyclical gear train, such as a planetary gearsystem, star gear system or other known gear system, with a gearreduction ratio of greater than about 2.3.

In one disclosed embodiment, gas turbine engine 20 includes a bypassratio greater than about ten (10:1) and the fan diameter issignificantly larger than an outer diameter of low pressure compressor44. It should be understood, however, that the above parameters are onlyexemplary of one embodiment of a gas turbine engine including a gearedarchitecture and that the present disclosure is applicable to other gasturbine engines.

A significant amount of thrust is provided by bypass flow B due to thehigh bypass ratio. Fan section 22 of engine 20 is designed for aparticular flight condition—typically cruise at about 0.8 Mach and about35,000 feet. The flight condition of 0.8 Mach and 35,000 ft., with theengine at its best fuel consumption—also known as “bucket cruise ThrustSpecific Fuel Consumption (‘TSFC’)”—is an industry standard parameter ofpound-mass (lb_(m)) of fuel per hour being burned divided by pound-force(lb_(f)) of thrust the engine produces at that minimum point.

“Low fan pressure ratio” is the pressure ratio across the fan bladealone, without a Fan Exit Guide Vane (“FEGV”) system. The low fanpressure ratio as disclosed herein according to one non-limitingembodiment is less than about 1.50. In another non-limiting embodimentthe low fan pressure ratio is less than about 1.45.

“Low corrected fan tip speed” is the actual fan tip speed in ft/secdivided by an industry standard temperature correction of [(T_(ram)°R)/518.7]^(0.5). The “Low corrected fan tip speed”, as disclosed hereinaccording to one non-limiting embodiment, is less than about 1150ft/second.

The example gas turbine engine includes fan 42 that comprises in onenon-limiting embodiment less than about 26 fan blades. In anothernon-limiting embodiment, fan section 22 includes less than about 20 fanblades. Fan section 22 can be surrounded by fan containment case 62,including a ballistic inner surface to absorb impacts from one or morefugitive fan blades in a blade-off condition, which may occur due toforeign object damage (FOD event).

Moreover, in one disclosed embodiment low pressure turbine 46 includesno more than about 6 turbine rotors schematically indicated at 34. Inanother non-limiting example embodiment low pressure turbine 46 includesabout 3 turbine rotors. A ratio between number of fan blades 42 and thenumber of low pressure turbine rotors is between about 3.3 and about8.6. The example low pressure turbine 46 provides the driving power torotate fan section 22 and therefore the relationship between the numberof turbine rotors 34 in low pressure turbine 46 and number of blades 42in fan section 22 disclose an example gas turbine engine 20 withincreased power transfer efficiency.

FIG. 2A shows a flanged portion of fan containment case 62, and FIG. 2Bshows a cross-section of case 62. FIGS. 2A and 2B also include bodysection 64, flange section 66, transition section 68, wraps 70, matrixcomposition 72, body section outer diameter 74, flange section outerdiameter 76, component circumferential direction 78, and component axialdirection 79.

Fan containment case 62 includes a generally tubular (e.g. cylindricalor frustoconical) body section 64 and flange section 66 integrallyjoined to body section 64 via transition section 68. Flange section 66is upturned relative to body section 64 such that flange section outerdiameter 76 is greater than body section outer diameter 74.Alternatively, flange section outer diameter 76 can optionally be lessthan body section outer diameter 74 such that flange section 66 isdownturned relative to body section 64. Optional transition section 68,disposed between the flange radius and body section 64, further reducesstrain when forming the radius and flange as one integral component ascompared to attaching a separate flange to the case.

In this example, case 62 is a composite material with a plurality ofwoven fibers encompassed within a matrix. Here, case 62 includes aplurality of braided fiber wraps 70 encompassed within a cured matrixcomposition 72. Each wrap 70 may be separate or they may be in acontiguous sheet. The woven fibers may be ceramic such as siliconcarbide, or they may be carbon fibers. Additionally and/oralternatively, the woven fibers can include by way of non-limitingexample, aramid (e.g., Kevlar®), fiberglass, polyethylene, etc. Thefibers may be coated to improve adherence with the matrix, or they maybe uncoated. The matrix may be ceramic, epoxy resin, or any othersuitable material with appropriate mechanical characteristics. Fiberwraps 70 can be aligned with its braided fibers or tows in order tocustomize mechanical properties of case 62. There are some benefits toaligning axial tows (i.e., bundles of fiber arranged generallylengthwise along a fabric sheet) into a component circumferentialdirection 78. For example, this arrangement may increase hoop strengthfor larger components as compared to arranging the fibers in a componentaxial direction 79. In this illustrative example, sufficient hoopstrength allows a fan containment case to absorb one or more blades lostin an FOD event as noted above. The case can then minimize bladeingestion and absorb blade-off energy without impaired load bearingcapabilities. However, there are other shortcomings.

To simplify manufacturing, composite components may be manufacturedusing a single fabric preform comprising woven and braided tows. Whilesmaller radius composite components (e.g. turbine shafts) often haveaxial tows aligned axially along the shaft, larger radius components,such as a fan containment case, are much more difficult to manufactureusing an axially oriented preform. However, if the axial tows of thepreform are arranged along the circumferential component direction,continuous fibers in the axial tows do not easily deform to conform tothe changing diameter of an upturned or downturned flange. Removing theaxial tows from the flange area of the preform can allow the remainingbias tows to easily shear and bend relative to one another. But removingthe axial tows greatly reduces structural properties of the flange,including lower bearing strength, lower hoop strength, and lowerstiffness. Manually inserting axial tows during layering and windingaround the mandrel may be done, but this greatly impairs themanufacturing process, and can introduce defects (e.g. wrinkling).

FIG. 3A shows an example of a wrapped fabric preform 80 for use informing a composite case, and also includes wraps 70A, 70B, 70C,component circumferential direction 78, component axial direction 79,wall inner surface 84, wall outer surface 86, preform body section 88,preform flange section 90, preform transition section 92, first biaxiallayers 94A, and second biaxial layers 94B. FIG. 3B shows wrapped preform80 with upturned preform flange section 90 and preform transitionsection 92 adjacent preform body section 88.

FIG. 3A shows an example fabric wrapped preform 80 for use in forming anexample embodiment of composite case 62. For illustrative purposes,preform 80 includes three wraps 70A, 70B, 70C between wall inner surface84 and wall outer surface 86. Wrap 70A in this example corresponds tothe inner diameter of case 62 while wrap 70C corresponds to the outerdiameter. It will be understood that many embodiments will have morethan three wraps, but only three wraps are shown so as to simplify thevarious illustrations.

Wrapped fabric preform 80 is divided into preform body section 88,preform flange section 90, and preform transition section 92, eachcorresponding to respective component body section 64, component flangesection 66, and component transition section 68 (shown in FIGS. 2A and2B). Body preform section 88 comprises a plurality of axial tows braidedwith at least a plurality of first bias tows and a plurality of secondbias tows (shown in FIG. 4A). As noted above, the axial tows in preformbody section 88 can be configured generally around the circumference ofthe component by arranging the axial direction of preform 80 togenerally align with component circumferential direction 78. This canincrease hoop strength of the finished component. Examples of axial andbias tows are shown in FIGS. 4A-4C.

To allow component flange section 66 to be formed integrally with bodysection 64, preform flange section 90 does not include axial tows.Preform flange section 90 can then be reinforced by additional bias towsas explained below. In certain embodiments, such as is shown in thisexample, component transition section 68 is shown with preformtransition section 92 where each wrap 70A, 70B, 70C has an interfacebetween preform body section 88 and preform flange section 90respectively formed with and without axial tows. Preform transitionsection 92 can be formed to have adjacent interfaces transversely offsetfrom each other for each radially adjacent wrap 70A, 70B, 70C.

In this example, preform flange section 90 includes first biaxial layers94A and second biaxial layers 94B each formed as part of one wrap 70A,70B, 70C. For each wrap 70A, 70B, 70C, first biaxial layer 94A isdefined by first and second bias tows extending from preform bodysection 88 into preform flange section 90. This allows for a flangedcomponent with an integral flange and no breaks between the flange andthe body section. Second biaxial layer(s) 94B can be added to preformsheet 80 prior to wrapping and consolidation in order to reinforcepreform flange section 90 and the resulting component flange section 66.In this example, first biaxial layer is oriented respectively at anglesmeasuring about 60° and about −60° relative to an axial direction of thesheet, while second biaxial layer 94B is oriented respectively at anglesmeasuring about 30° and about −30° relative to an axial direction of thesheet. This can be seen in FIGS. 4A-4C.

FIG. 3B shows wrapped preform 80 with preform flange section 90 andpreform transition section 92 upturned to eventually form the componentflange section 68 (shown in FIGS. 2A and 2B). This may be done, forexample using a mandrel to layer the wraps 70A, 70B, 70C, then upturnpreform flange section 90 and optionally preform transition section 92.

As noted above, with axial tows in the preform flange and transitionsections, wrapped preform 80 would experience too much strain with theincreased radial dimension of the flange. Adding a separate compositeflange segment after formation of the cured component body introduceslocalized stresses and weakness. Merely removing the axial tows in thesesections weakens the flange, while adding axial tows after upturning theflange section is more complex and makes the part more prone to defects.

In contrast, second biaxial layer 94B reinforces the first integralbiaxial layer 94A in preform flange section 90 as well as optionalpreform transition section 92. In preform transition section 92,interfaces 96A, 96B, 96C between preform body section 88 and preformflange section 90 are offset from one another in the component axialdirection. In this example, inner flange 70C has a wider two-layersection as compared to inner flange 70A such that the curvature inpreform transition section 92 experiences reduced strain on the biastows when the flange is turned, such as on the mandrel.

FIGS. 4A-4C depict example arrangements of tows that can be usedrespectively for preform body section 88, first biaxial layer 94A, andsecond biaxial layer 94B shown in FIGS. 3A and 3B. FIGS. 5A-5Dillustrate the results of steps of a method for forming an exampleunwrapped fabric preform sheet for a flanged component (e.g., wrappedpreform 80 shown in FIGS. 3A-3B) from a triaxially braided sheet offabric.

FIG. 4A shows triaxial fabric 100, with axial tows 102, first bias tows104A, and second bias tows 104B. Triaxial fabric 100 is braided to haverespective pluralities of first and second bias tows 104A, 104B braidedat about a 60° bias in either direction relative to axial tows 102. Thisarrangement is known as −60°/0°/60°. In this particular example of−60°/0°/60° triaxial fabric, each tow, or bundle of individual fibers,is approximately 60° offset from each adjacent tow when viewed normal tothe sheet as shown in FIG. 4A. Thus it will be apparent that anyplurality of parallel tows in this example can be considered axial tow102 and aligned with the circumferential direction of the component asdescribed above, then those disposed about 60° clockwise relative toaxial tows 102 can be first bias tows 104A, while second bias tows 104Bare generally braided to be about 60° counterclockwise, or −60° relativeto axial tows 102. It will also be appreciated that axial tows 102 maynot be precisely aligned with the component circumferential direction,but in certain cases may be slightly offset by several degrees from thecomponent circumferential direction. One reason can be in order toaccommodate noncylindrical (e.g., frustoconical) arrangements of thetubular body section.

FIG. 4B shows first biaxial fabric 106, with first bias tows 108A andsecond bias tows 108B. Here, the first and second bias tows are alsobraided at about a 60° bias in either direction relative to an axialdirection. However, fabric 106 is missing axial (0°) tows with first andsecond bias tows 108A, 108B offset by about 120° relative to each other.This arrangement is known as −60°/60°, and can be arranged such thatfirst and second bias tows 108A, 108B are offset about 60° respectivelyfrom the axial fabric direction and the component circumferentialdirection. In certain embodiments, such as is described in FIGS. 5A and5C below, the first and second (−60° and 60°) bias tows of first biaxialfabric 106 can be contiguous with first and second (−60° and 60°) biastows 104A, 104B of triaxial fabric 100 such that the first braidedflange layer and the first braided transition layers are defined byfirst and second bias tows extending into these sections.

FIG. 4C shows second biaxial fabric 110, with third bias tows 112A andfourth bias tows 112B. In this example, the first and second bias towsare braided about 60° apart, or at about a 30° bias in either directionrelative to an axial direction (0°). However, fabric 110 is also missingaxial (0°) tows. This arrangement is known as −30°/30°, where third biastows 112A are approximately 30° clockwise from the axial direction ofthe fabric, and fourth bias tows 112B are braided about 30°counterclockwise. In certain embodiments, third and fourth bias tows112A, 112B can be used to reinforce first and second bias tows 108A,108B. For example, as described in FIGS. 5B and 5C below, third andfourth (−30° and 30°) bias tows 112A, 112B of second biaxial fabric 110can reinforce first and second (−60° and 60°) bias tows 108A, 108B.

FIGS. 5A-5D illustrates various steps of making a preform for a flangedcomposite component. FIG. 5A depicts a first article of fabric 120, suchas a sheet, laid out prior to wrapping. This sheet can form the basis ofa wrapped fabric preform for a flanged component, such as wrappedpreform 80 shown in FIGS. 3A and 3B.

The relative positions of what will become preform body section 88,preform flange section 90, and preform transition section 92 aredelineated here. Sheet 120 can initially have uniform triaxially braidedtows throughout all of what will become preform sections 88, 90, 92 inthe final wrapped preform 80. The triaxial braid may be, in anon-limiting example, arranged in an orientation such as −60°/0°/60° asis shown in FIG. 4A. In this non-limiting example, orientation of sheet120 with axial tows 102 (0°) along an axial direction of the sheetallows axial tows 102 to be arranged generally along the componentcircumferential (hoop) direction 78 (as shown in FIG. 2A). Thehorizontal or transverse orientation of sheet 120 corresponds generallyto an axial dimension 79 of the composite component (e.g., case 62 shownin FIG. 2A). Thus, first article of fabric 120 has a width transverse tothe axial tows that is equal to or greater than a sum of a longitudinaldimension of a corresponding component body section 64, a radialdimension of a corresponding component flange section 66, and a lengthof an optional transition section 68 linking the component body section64 and flange section 66. The vertical dimension of sheet 120 is dividedinto three contiguous wraps 70A, 70B, 70C, each wrap correspondingroughly to one circumferential dimension of wraps 70A, 70B, 70C shown inFIG. 3B.

FIG. 5B shows the result of a process step where axial tows (e.g., axialtows 102 in FIG. 4A) is removed from a portion of the sheet 120. Thisleaves behind a first portion 122 and second portion 124. First portion122 is a biaxial braided region absent axial tows. At this stage, firstportion 122 includes only a first layer 94A of biaxial −60°/60° fabricin preform flange section 90 and optional preform transition section 92.With the example fabrics described above, axial tows 102 are removedfrom the −60°/0°/60° fabric shown in FIG. 4A, and thus first fabricportion 122 now resembles first biaxial fabric 106 shown in FIG. 4B.Second portion 124 however, can remain contiguous with axial tows 102,such that bias braids of the first layer 94A remain contiguous with biasbraids of the triaxial fabric in the second portion 124, whichcorresponds to preform body section 88.

FIG. 5C next shows a second, separate biaxially braided sheet 128, whichcan conform generally to first fabric portion 122. Second sheet 128 isfor example, biaxially braided −30°/30° fabric without axial tows asshown in FIG. 4C. In FIG. 5D, second sheet 128 can then be temporarilysecured, such as by a thermoplastic thread (not shown), along firstfabric portion 122 to form a reinforced first fabric portion 122′comprising first and second biaxial layers 94A, 94B. The finishedpreform sheet as shown in FIG. 5D now includes a reinforced firstportion 122′ with two alternating layers 94A, 94B each with at least twobraided bias tows absent axial tows. Second portion 124 has triaxiallybraided fabric including axial tows. The thermoplastic thread may besubstituted by any other temporary retention article that dissolves,vaporizes, or is otherwise removed. The retention article can also bepermanent so long as it is unobtrusive and does not interfere with useof the finished product.

Once the completed preform sheet is finished, it can then be arrangedand wrapped such that the axial tows are aligned with a circumferentialdirection of the component. To complete the case or other flangedcomponent, the unwrapped fabric preform shown in FIG. 5D can be wrappedand secured over a mandrel (not shown). The mandrel or other formingtool having a portion for upturning the flange section relative to thebody section in the manner shown in FIGS. 3A and 3B. The wrapped preformcan then be impregnated with an uncured matrix composition. Theimpregnated preform is cured to form a composite case precursor, whichis then processed, such as by machining, into a final composite case.

While this example has been described with respect to three wraps 70A,70B, 70C, this is merely illustrative. It will be appreciated that manyembodiments of a fabric preform sheet will contain different numbers ofwraps 70 customized to the needs of a particular flanged component suchas case 62. For example, the axial dimension of a single wrap 70A, 70B,70C need not be exactly equal to the local circumferential dimension ofthe component. If, for example, the axial dimensions of adjacent wraps70A, 70B were identical to the local circumferential dimension of thecomponent, the interface between adjacent wraps would end up at the samecircumferential location around preform transition region 92. In somecases, this can cause localized weakening of the flange. Thus the axialdimension of wraps 70A, 70B, 70C may alternatively be greater or lessthan the local circumferential component dimension, such that theinterfaces between adjacent wraps (e.g., wraps 70A and 70B) are notdirectly adjacent in the component radial direction.

Discussion of Possible Embodiments

The following are non-exclusive descriptions of possible embodiments ofthe present disclosure.

A fabric preform for a composite component according to an exemplaryembodiment of this disclosure, among other possible things, includes apreform body section and a preform flange section. The preform bodysection includes a plurality of axial tows aligned along an axialdirection of the preform. The axial tows are braided with at least aplurality of first bias tows and a plurality of second bias tows. Thepreform flange section includes a first braided flange layer and asecond braided flange layer. The first braided flange layer is definedby the first and second bias tows of the preform body section extendinginto the preform flange section, neither the first nor second braidedflange layers having axial tows.

The fabric preform of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing fabric preform, wherein the axialdirection of the preform generally corresponds to a componentcircumferential direction.

A further embodiment of any of the foregoing fabric preforms, whereinthe preform body section comprises triaxially braided fabric with thefirst bias tows oriented at an angle measuring about 60° relative to theaxial direction of the preform, and the second bias tows oriented at anangle measuring about −60° relative to the axial direction of thepreform.

A further embodiment of any of the foregoing fabric preforms, whereinthe second braided flange layer comprises biaxially braided fabric witha plurality of third bias tows and a plurality of fourth bias tows.

A further embodiment of any of the foregoing fabric preforms, whereinthe plurality of third bias tows are oriented at an angle measuringabout 30° relative to an axial direction of the preform, and theplurality of fourth bias tows are oriented at an angle measuring about−30° relative to the axial direction of the preform sheet.

A further embodiment of any of the foregoing fabric preforms, whereinthe fabric preform further comprises a preform transition sectionincluding a first braided flange layer defined by the first and secondbias tows of the preform body section extending into the preformtransition section.

A further embodiment of any of the foregoing fabric preforms, whereinthe first braided flange layer of the preform transition section doesnot have axial tows.

A further embodiment of any of the foregoing fabric preforms, whereinthe preform transition section comprises a second braided transitionlayer extending into the second braided flange layer.

A further embodiment of any of the foregoing fabric preforms, whereinthe preform includes a plurality of axially contiguous wraps, each wrapcomprising a braid interface disposed transversely between the preformbody section and the preform transition section, each braid interfacecircumferentially offset from radially adjacent braid interfaces.

A gas turbine engine component according to an exemplary embodiment ofthis disclosure, among other possible things, includes a tubular bodysection and a flange section. The tubular body section includes aplurality of fiber wraps encompassed within a matrix composition. Theplurality of body section fiber wraps each include a plurality of axialtows braided with at least a plurality of first bias tows and aplurality of second bias tows. The axial tows are generally alignedalong a component circumferential direction. The flange section includesa plurality of fiber wraps encompassed within the matrix composition,and each include a first braided flange layer and a second braidedflange layer. The first braided flange layer is defined by at least thefirst and second bias tows of the body section. Neither the first norsecond braided flange layers have axial tows.

The gas turbine engine component of the preceding paragraph canoptionally include, additionally and/or alternatively, any one or moreof the following features, configurations and/or additional components:

A further embodiment of the foregoing gas turbine engine component,wherein the flange section is upturned relative to the body section suchthat a flange section outer diameter is greater than a body sectionouter diameter.

A further embodiment of any of the foregoing gas turbine enginecomponents, wherein the component is a fan containment case.

A further embodiment of any of the foregoing gas turbine enginecomponents, wherein the second braided flange layer includes a pluralityof third bias tows braided with a plurality of fourth bias tows.

A further embodiment of any of the foregoing gas turbine enginecomponents, wherein the component further comprises a transition sectionincluding a plurality of braid interfaces disposed at a flange end ofthe body section, each braid interface circumferentially offset fromradially adjacent braid interfaces.

A method for making a fabric preform for a composite component accordingto an exemplary embodiment of this disclosure, among other possiblethings, includes laying out a first article of fabric having a pluralityof axial tows braided with a plurality of first bias tows and aplurality of second bias tows. Axial tows are removed from a firstportion of the first article of fabric, leaving the first fabric portionbraided absent an axial tow, and a second fabric portion braided withaxial tows. A second article of fabric is disposed along to the firstarticle of fabric along the first fabric portion to form a reinforcedfirst fabric portion, the second article of fabric absent an axial tow,such that the reinforced first fabric portion includes a first braidedlayer and a second braided layer each absent an axial tow.

The method of the preceding paragraph can optionally include,additionally and/or alternatively, any one or more of the followingfeatures, configurations and/or additional components:

A further embodiment of the foregoing method further comprises arrangingthe first article of fabric such that the axial tow in at least thesecond fabric portion is substantially aligned with a circumferentialorientation of the composite component.

A further embodiment of any of the foregoing methods, wherein the firstarticle of fabric comprises a plurality of wraps, an axial dimension ofeach wrap being approximately equal to a local circumferential dimensionof the component.

A further embodiment of any of the foregoing methods, wherein thereinforced first fabric portion defines a preform flange section.

A further embodiment of any of the foregoing methods, wherein the firstarticle of fabric is contiguous triaxially braided fabric with the atleast two bias tows oriented respectively at angles measuring about 60°and about −60° relative to the axial tow.

A further embodiment of any of the foregoing methods, wherein the twobias tows of the second article of fabric are oriented respectively atangles measuring about 30° and about −30° relative to the axial tow ofthe first article of fabric.

A method for making a composite case according to an exemplaryembodiment of this disclosure, among other possible things, includesforming a fabric preform according to any of the foregoing methods formaking a fabric preform. The fabric preform is secured over a mandrel,the mandrel including a portion for upturning the flange sectionrelative to the body section. The preform is impregnated with an uncuredmatrix composition. The impregnated preform is cured to form a compositecase precursor. The composite case precursor is processed into a finalcomposite case.

A fan containment case for a gas turbine engine according to anexemplary embodiment of this disclosure, among other possible things,includes manufacturing the case according any of the foregoing methods.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A fabric preform for a composite component, the fabric preformcomprising: a preform body section including a plurality of axial towsaligned along an axial direction of the preform, the axial tows braidedwith at least a plurality of first bias tows and a plurality of secondbias tows; and a preform flange section including a first braided flangelayer and a second braided flange layer, the first braided flange layerdefined by the first and second bias tows of the preform body sectionextending into the preform flange section, neither the first nor secondbraided flange layers having axial tows.
 2. The fabric preform of claim1, wherein the axial direction of the preform generally corresponds to acomponent circumferential direction.
 3. The fabric preform of claim 1,wherein the preform body section comprises triaxially braided fabricwith the first bias tows oriented at an angle measuring about 60°relative to the axial direction of the preform, and the second bias towsoriented at an angle measuring about −60° relative to the axialdirection of the preform.
 4. The fabric preform of claim 1, wherein thesecond braided flange layer comprises biaxially braided fabric with aplurality of third bias tows and a plurality of fourth bias tows.
 5. Thefabric preform of claim 4, wherein the plurality of third bias tows areoriented at an angle measuring about 30° relative to an axial directionof the preform, and the plurality of fourth bias tows are oriented at anangle measuring about −30° relative to the axial direction of thepreform sheet.
 6. The fabric preform of claim 5, further comprising apreform transition section including a first braided flange layerdefined by the first and second bias tows of the preform body sectionextending into the preform transition section.
 7. The fabric preform ofclaim 6, wherein the first braided flange layer of the preformtransition section does not have axial tows.
 8. The fabric preform ofclaim 7, wherein the preform transition section comprises a secondbraided transition layer extending into the second braided flange layer.9. The fabric preform of claim 6, wherein the preform includes aplurality of axially contiguous wraps, each wrap comprising a braidinterface disposed transversely between the preform body section and thepreform transition section, each braid interface circumferentiallyoffset from radially adjacent braid interfaces.
 10. A gas turbine enginecomponent comprising: a tubular body section including a plurality offiber wraps encompassed within a matrix composition, the plurality ofbody section fiber wraps each including a plurality of axial towsbraided with at least a plurality of first bias tows and a plurality ofsecond bias tows, the axial tows generally aligned along a componentcircumferential direction; a flange section including a plurality offiber wraps encompassed within the matrix composition, the plurality offlange section fiber wraps each including a first braided flange layerand a second braided flange layer, the first braided flange layerdefined by at least the first and second bias tows of the body section,neither the first nor second braided flange layers having axial tows.11. The gas turbine engine component of claim 10, wherein the flangesection is upturned relative to the body section such that a flangesection outer diameter is greater than a body section outer diameter.12. The gas turbine engine component of claim 10, wherein the componentis a fan containment case.
 13. The gas turbine engine component of claim10, wherein the second braided flange layer includes a plurality ofthird bias tows braided with a plurality of fourth bias tows.
 14. Thegas turbine engine component of claim 10, further comprising atransition section including a plurality of braid interfaces disposed ata flange end of the body section, each braid interface circumferentiallyoffset from radially adjacent braid interfaces.
 15. A method for makinga fabric preform for a composite component, the method comprising:laying out a first article of fabric having a plurality of axial towsbraided with a plurality of first bias tows and a plurality of secondbias tows; removing axial tows from a first portion of the first articleof fabric, leaving the first fabric portion braided absent an axial tow,and a second fabric portion braided with axial tows; and disposing asecond article of fabric along the first fabric portion to form areinforced first fabric portion, the second article of fabric absent anaxial tow, such that the reinforced first fabric portion includes afirst braided layer and a second braided layer each absent an axial tow.16. The method of claim 15, further comprising: arranging the firstarticle of fabric such that the axial tow in at least the second fabricportion is substantially aligned with a circumferential orientation ofthe composite component.
 17. The method of claim 15, wherein the firstarticle of fabric comprises a plurality of wraps, an axial dimension ofeach wrap being approximately equal to a local circumferential dimensionof the component.
 18. The method of claim 15, wherein the reinforcedfirst fabric portion defines a preform flange section.
 19. The method ofclaim 15, wherein the first article of fabric is contiguous triaxiallybraided fabric with the at least two bias tows oriented respectively atangles measuring about 60° and about −60° relative to the axial tow. 20.The method of claim 15, wherein the two bias tows of the second articleof fabric are oriented respectively at angles measuring about 30° andabout −30° relative to the axial tow of the first article of fabric. 21.A method for making a composite case comprising: forming a fabricpreform according to the method of claim 15; securing the fabric preformover a mandrel, the mandrel including a portion for upturning the flangesection relative to the body section; impregnating the preform with anuncured matrix composition; curing the impregnated preform to form acomposite case precursor; and processing the composite case precursorinto a final composite case.
 22. A fan containment case for a gasturbine engine manufactured according to the method of claim 21.